What a shame about your son. And of course he is not going to say no dad no McDonalds, think I'll have a salad....Your Ex sounds like a bit of a twit. Oh well, back to the drawing board with your boy...at least he's haqd some sucess before?
My youngest carried a lot of weight around that age, got called fat boy at school, etc ,etc but also a big build of a lad, loves food and really resisted "diet" thoughts.
At 15 and a half he is still a solid figure of a man/boy but not fat, just a large framed man. Shoulders and chest thaat go on and on...
He'll never be small, but he is not fat in the least. Just grew into his weight - didn't diet or resrict his eating. So I'd imagine your boy wil grow into his weight as puberty strikes too?